A touch of evil can bring fitness benefits. Daniel Craig as James Bond in Casino Royale (2006). Photograph: Reuters

Irresistible rascals

From a nice girl, aged 37Dear Carole, Why do girls – even nice girls – fall for bad boys, even when the girls in question are 37 and should know much better? My friends and I don't understand ourselves.

These types of males tend to favour short-term relationships (including one night stands) over long-term relationships. They also attempt to compete with other males by poaching mates for brief affairs.

Research has shown that a touch of evil can bring fitness benefits: these males tend to have more female partners and thus more reproductive opportunities than other males. The fictional character of James Bond is frequently cited as possessing dark triad traits.

Although the dark triad personality type appears to be universal in human society, having been identified in 57 countries, it does exact real costs – otherwise bad boys would be more common. Those exhibiting dark triad behaviour need to prey on the cooperative and unsuspecting.

If bad boys stay in one place and among the same group of humans for too long their psychopathy will be exposed. It has been predicted that this evolutionary strategy can only succeed if bad boys manage to achieve anonymity or lead an itinerant lifestyle.

Evolutionary-anthropological research on hunter gatherers, such as the !Kung San of the Kalahari, has shown that successful, risk-taking hunters – who "bring home the bacon" for the group – get the most mating opportunities.

As a single trait, successful risk-taking is universally appreciated as a sign of good genes. The combination of brave, risk-taking behaviour is frequently attractive to females in the short-term. But in the long term, although females remain attracted to bravery and risk-taking they also look for the crucial additional trait of altruism.

Ironically, "nice girls" may be the only females who tolerate the dark triad male personality, forgiving these naughty boys and inadvertently giving them yet another chance to misbehave.

Are you prepared to be a single mother? A bad boy son who survives all the risk-taking behaviour to reach reproductive age may make you a granny many times over, but are you really looking for quantity over quality?

You need to ask yourself this: "Do I want to be another notch on this man's bedpost, or would it be wiser to hold out for a brave altruist?"